First Battle of the Isonzo

The First Battle of the Isonzo was fought from 23 June to 7 July 1915 at the start of Italy's involvement in World War I. Italy attempted an offensive against Austria-Hungary along the Isonzo River in Slovenia, but the Royal Italian Army failed to break through the Austro-Hungarian Army's lines, leading to stalemate on the Italian front.

Background
Since 1882, Italy had been a member of the Triple Alliance with Germany and Austria-Hungary. At the outbreak of World War I, it declared neutrality. Italy's alliance with Austria-Hungary and Germany had always been unpopular in Italy, since most Italians regarded Austria-Hungary as their traditional enemy. War with Turkey in 1911-12 had revealed the weakness of Italy's armed forces and put a heavy strain on the economy. In 1914, anti-war sentiment was strong.

History
Italy aspired to the status of a major European power, despite an inadequate level of economic development. It had territorial ambitions in the Mediterranean, the Balkans, and Africa, as well as around its northeastern border, where a substantial number of Italians lived under Austro-Hungarian rule.

When war broke out in August 1914, the Italian prime minister, Antonio Salandra, saw the conflict as an opportunity to fulfill these aspirations. He adopted an attitude that he dubbed sacro egoismo ("sacred self-interest"), which meant offering to join the side that promised Italy the best deal. Germany urged Austria-Hungary to cede some disputed territory to Italy in exchange for Italian entry into the war, but the Austro-Hungarians were reluctant to comply. They grudgingly agreed to offer it the Trentino region in March 1915, but this was too little too late.

Treaty of London
By spring 1915, the Italian government was leaning heavily toward the Allies, who were promising Italy substantial territory in enemy countries if it entered the war on their side. Allied negotiators held out the prospect of Italy expanding its borders to include South Tyrol and Trentino, Trieste, and part of the Dalmatian coast. They also proposed an Italian protectorate over Albania, recognition of Italian control of the Dodecanese islands, colonies in Africa, and a share in a future carve-up of the Ottoman Empire. This was enough to persuade Salandra and his foreign minister, Giorgio Sonnino, to sign the Treaty of London with the Allies on 26 April. Under the terms of the treaty, which remained secret, Italy had to declare war on the Central Powers within a month. This was not easily done. In early May, neutralists in the Italian parliament voted Salandra out of office, but King Victor Emmanuel III, who was pro-war, reinstated him. Italian nationalists, including the prominent poet Gabriele d'Annunzio, mounted a passionate propaganda campaign in favor of joining the war. On 23 May, Italy declared war on Austria-Hungary. Despite Italy's promise in the Treaty of London, its declaration of war on Germany did not follow until 1916. Austria-Hungary was faced with the task of sustaining a war on three fronts - against Russia, Serbia, and Italy - which could have quickly proved disastrous. But the timing of Italy's declaration of war was fortuitous for Austria-Hungary because at that very moment the successful Gorlice-Tarnow Offensive was relieving the pressure on Austro-Hungarian forces fighting the Russians on the Eastern Front.

The Isonzo Campaign
Defending their 370-mile border with Italy would have been difficult for the Austro-Hungarian Army had it not been for the terrain. Most of the frontier consisted of impassable mountain peaks, except in Trentino, where the mountain barrier was traversed by a number of passes. Italian Chief of Staff Luigi Cadorna chose to concentrate his forces at the eastern end of the border, where the Isonzo valley offered a corridor into Austro-Hungarian territory.

The Isonzo was no easy option for the Italiasn, however, for the Austro-Hungarian forces occupied defensive positions - some blasted out of rock with dynamite - on the ridges, blocking progress from the coastal plain and at the northern end of the valley. Cadorna opened the First Battle of the Isonzo with an offensive on 23 June. The Italian armies were short of heavy artillery. Their best troops, such as the Alpini and the Bersaglieri, were impressive, but many others were poorly trained peasant conscripts from southern Italy who had little emotional connection with the north of the country.

The initial Isonzo offensive failed, despite the Austro-Hungarians being outnumbered by the Italians, as did three more Isonzo offensives before the end of 1915. Italy lost around 27,000 soldiers in the four battles, and the ground gained was minimal. Losses on the Austro-Hungarian side were also heavy. Shells exploding on the rocky terrain showered sharp rock fragments over a wide area, causing more casualties per shell than in the soft soil of France.

The Austro-Hungarians clung to their defensive positions and were gradually reinforced. Cadonra, a much feared commander, dismissed many generals and imposed brutal discipline on troops, but he had no tactical or strategic solution to the stalemate on the Isonzo Front.

Aftermath
The deadlock on the Italian front lasted for almost two and a half years, until it was ended by a victory for the Central Powers at Caporetto (now Kobarid in Slovenia). Austria-Hungary's position was also strengthened by the defeat of Serbia in the winter of 1915-16. This allowed the Austro-Hungarians to mount an initially successful offensive at Asiago in Trentino in May 1916, although without decisive results. The Italian achieved a limited victory at Gorizia (the Sixth Battle of the Isonzo) in August 1916 after Austria-Hungary diverted troops to respond to the Russian Brusilov Offensive.

The Italians renewed their Isonzo Campaign in spring 1917, advancing to within 9 miles of Trieste in June. They reached the Eleventh Battle of the Isonzo in September 1917. In October, a joint German and Austro-Hungarian offensive shattered the Italian line at Caporetto.